The Department of Soil Science is pleased to announce the Leo M. Walsh Distinguished Lecture in Soil Science on Wednesday, Apr. 19 at 3:30 pm in Soils Building, room 270.

Dr. Yan Jin (Professor of Soil & Environmental Physics, Francis Alison Professor/Edward F. & Elizabeth Goodman Rosenberg Professor, Dept. of Plant and Soil Sciences, at the University of Delaware-Newark) will present a lecture entitled “Microbes Engineer Microhydrological Niches in Soil”.

Abstract: Soil bacteria can alter biophysical properties of their surrounding soil environment to alleviate undesirable fluctuations of water content through production of extracellular polymeric substances (EPS). The physical mechanisms by which EPS mediate such changes are complicated due largely to the diverse EPS being produced by different microorganisms and in response to different environmental conditions. Measurements of water retention and evaporation with soils treated with a wild type Bacillus subtilis variant (UD1022) and its two mutants show increased soil water retention and reduced evaporation because bacterial EPS can modify soil matrix structure, increase pore and water film connectivity in drying soil, and lower local drying rate by changing the viscosity and surface tension of soil solution. Imaging with neutron radiography show significant difference in dry-out progression between control and bacteria-treated samples as well as the heterogeneous characteristic of water distribution during evaporation. These findings provide the critical link between pore-scale mechanisms and macroscopic changes of soil water dynamics and hydraulic properties mediated by microbes/EPS in the rhizosphere and other biological hotspots. They can be used as scientific basis for harnessing beneficial functions of soil bacteria to reduce plant abiotic stress, facilitate ecosystem restoration, and improve soil functioning.

The Lecture is made possible by the generosity of Leo M. Walsh (former CALS Dean and Professor of Soil Science) and the Leo M. Walsh Distinguished Lecture in Soil Science Fund. For more information, contact Carol Duffy at cjduffy@wisc.edu or (608) 262-0485.